Re: [ARSCLIST] delamination of CDs

[Joe_Iraci@xxxxxxxxx]

Read-only CDs such as audio CDs, consist of a base layer with pits moulded
into the top side of the polycarbonate base. On top of the base is a thin
metal reflective layer, that is deposited by vacuum deposition. This metal
layer is protected with a lacquer layer that is applied by spin-coating and
then a label is screened onto the disc. For recordable CDs or CD-Rs, there
is a spiral groove embedded in the plastic base (no pits). Then a dye layer
is spun coated onto the base, followed by metal layer, etc. No adhesive
like you may be thinking is used to attach the layers together.

DVDs on the other hand are two discs, half the thickness of a CD, glued
together top side to top side. The adhesive used varies depending on the
format of DVD (DVD read-only, DVD-R, DVD-RW) and the composition of the
metal reflective layers.

Joe Iraci
Senior Conservation Scientist
Canadian Conservation Institute



             Bev Lambert
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             06/07/2005 11:56
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I am not a preservation scientist or even an knowledgeable audiophile, but
an archives conservator charged with the task of researching best practises
for digitization of magnetic media.  So, my question may seem naive: is it
known whether CDs are laminated with an adhesive?  and if so, is it known
which adhesive this is?  It seems to me that a different process. such as
heat or pressure lamination would be more appropriate?
Bev Lambert, Archives Conservator
Provincial Archives at The Rooms
St. John's, Newfoundland, Canada